Broad-band omnidirectional spherical lens antenna with rotating amplitude modulationpattern



June 1961 D. F. BOWMAN 2,990,545

BROAD-BAND OMNIDIRECTIONAL SPHERICAL LENS ANTENNA WITH ROTATINGAMPLITUDE MODULATION PATTERN Filed June 17, 1958 4 Sheets-Sheet 1 D. F.BOWMAN June 27, 1961 ,990,545 BROAD-BAND OMNIDIRECTIONAL SPHERICAL LENSANTENNA WITH ROTATING AMPLITUDE MODULATION PATTERN Filed June 17, 1958 4Sheets-Sheet 2 INVENTOR. 1

.am/m A ear/WW Arraz/VEYJ June 27, 1961 BOWMAN 2,990,545

BROAD-BAND OMNIDIRECTIONAL SPHERICAL LENS ANTENNA WITH ROTATINGAMPLITUDE MODULATION PATTERN Filed June 17, 1958 4 Sheets-Sheet 3INVENTOR. j? 10.0 F BOW/144A Arrd/V'fi June 27, 1961 D BOWMAN 2,990,545

BROAD-BAND OMNIDIRE ONAL P ER L LENS ANTENNA 1 WITH ROTATING AMPLITUDEDUL 0N PATTERN Filed June 17, 1958 4 Sheets-Sheet 4 tates P n a2,990554'5- Y Y BROKE-BAND OMNIDIRECTIONAL SPHERICAL LENS ROTATING AMPLLTUDE MODULATION PATTERN- David F. Bowman, Wayne; Pa, .assignor to I-T-E"Circuit Breaker Company Philadelphia, Pa., a corporation ofPennsylvania.

Filed'June' 17, ,1'958,,Ser. No; 742,646 13 Claims. (Cl; 343-755)invention relates generally to directional transrrritting antenna; andmore particularly relates to novel antenna-for transmitting thedirectional radio pattern for the radio navigational system known asTacan.

TheTacan system has beendeveloped in recent years, initi'allytormilitary aircraft; being an abbreviation of tactical air navigation; Itoperates in the UHF spectrum, being assigned the range 960 me. to 1215mc. TIhBlOW band'Tacan range'is 960 to'1024 mc.; the high band, 1150 to12-15 mc. The intermediate band 1024 to 1150 mc. is usedfor'interrogation'of theTacan station by an aircraftfordistancedeterminations.

The CivihAeronautics Administration is setting up a system oftransmitting stations combining Tacan with civilian VHF omnirange orVOR. The latter system is'known as Vortac. One of the new requirementsfor the Tacantransrnitter antenna is that it be directly adaptable toefficiently transmit" its'patterned signals over any frequencyin eitheroftheTacanhighor 10W bands. The present invention provides novel antennasystems with broad band characteristics to accomplish this feature.

Another" important- Ci'vil Aeronautics Administration requirement is tohave the transmitted Tacan pattern be efiective over an elevation rangefrom the horizonto at least 60" above the-horizon." Such wide elevationcover age has been unattainable with prior antennae. Further; the newTacan transmitted signals are to be of higher gain than'heretofore,namely, to be six db over that of an isotropic source; The antennasystems ofthe' present invention accomplish these important anddesirable objec= tives.

In accordance with my invention, 1 utilize'a: dielectric sphere known asa Luneberg lens, and provide multiple or infinite point sources of theradio waves to be radiated from a circularpathon the sphere.'I'he-resultis 360 horizontal radio pattern of general toroidal formr'I' further incorporate therein modulators to shape the toroidal formwith fundamental and nine lobed modulations to constitute thecharacteristic Tacan pattern. Rotation of the modulated point sources at900 rpm. about the sphere results in the Tacan signal transmissionintercepted at 15 and 135 cycles persecond.

It is'accordinglya" primary object of the present invention to provide anovel transmitter antenna incorporating a dielectric sphere withmultiple radio point source thereabout to produce a generally toroidalpattern.

Another object ofthepresent invention is to provide a novel Tacanantenna? utilizing a dielectric sphere to transmit a'Tacanrpatternzwitha gain at the to elevation angles of six db over an isotropic source.

A further object of the present invention'is to provide a novel antennaincorporating a dielectric sphere to transmit a generally toroidal 360radio pattern with eifective signal strength from horizon to at least 60above the horizon.

Still another object of the present invention is to pro vide -a. novelantenna-system capable of efliciently transmitting a Ta'can-radiov arrayat any frequency over the: whole UHF Tacan band.

Still a further object of the present invention is to provide a novelTacan transmitter antenna that is efli-' I 2,990,545 Patented June 27,1961 1 2 cient; rugged and capable of long-time uninterrupted operation.

The aboveand further objects of the present invention willbecome moreapparent from the following description of exemplary embodimentsthereof, illustrated in the drawings, in which? FIGURE 1 is a polarrepresentation of anidealized radio Tacan pattern in a single elevationplane.

FIGURE-2 is a polar representation of the antenna radiationpattern in asingle azimuth plane as modulated with nine lobes.

FIGURE 3 is a polar representation of the antenna radiationpattern in asingle azimuth plane as modulated bythe fundamental frequency.

FIGURE 4 is a polar representation of the composite antenna radiationpattern per FIGURES 2 and 3;

FIGURE 5 is 'a diagrammatic showing of the operation of a Luneberg lenswith a single radio point source.

FIGURE 6 is a curve illustrating the relative signal strength of theLuneberg lens beam at angular deviations from the normal direction.

FIGURE 7 is a polar representation of thebeam emit ted from the' lens ofFIGURES.

FIGURE 8' is a perspectiveschematie diagram of the multiple or infiniteradio point sources for the spherical lens, .in accordance.with myinvention.

FIGURE 9 is a perspective illustration: of an. exem plary means forgenerating theradio point sources in the lensof FIGURE 8.

FIGURE 10 is across-section view through-a spherical antenna arrangementutilizing the signal feed means of FIGURE 9.

FIGURE: 11 is a plan view of the signal feed system of FIGURES 9 and 10incorporating modulator elements;

FIGURE 12 isan-enlarged cross-sectional view through the line 1.z-'-1-zof FIGURE 11', illustrating an exemplary modulator element.

FIGURE 13 is 'a diagrammatic showingof a. modified spherical lens:antenna in accordance with my invention:

FIGURE' 14 is. a polar representation: in: a single-elevation plane oftheradiation pattern of the antennaof FIGURE 13;

FIGURES 15, 16 and 17 are'illustrations of further forms which myantennamay assume inipractice;

FIGURE 18 is a polar representation in-wa singleazimuthal plane of the.radiation pattern of theantenna of FIGUREv l7.

FIGURES-19 and 20 are schematic showings of alternate. radio signal feedpositions with respect to the antenna hereof.

FIGURE 21 is plan view of the trigger disc of' the pulse generator.ofithe invention system. per FIGURE 22;

FIGURE 22 is a cross-sectional view vertically'through acompleteiantennastructure in accordance to thepreseut invention.

In FIGURE. 1, I have represented in polar form the new Civil:Aeronautics Administrationrequirements asto theradiated Tacan patterninan elevation plane. Radial lobes- 31, 31a. are specified to be greaterin amplitude than the=carrier level, represented in FIGURE-2 bythebroken uniform circlefil with center c. The troughs 31a are specified tobe 21% less in amplitude than the carrier level.

The Tacan pattern also requires a fundamental modulation as representedby FIGURE 3. This may be the essentially circular pattern- 33, havingits center c' displaced from reference center c whereby in amplitude thepeak of curve 33 is 21% greater and the valley of curve 33 is 21% lessthan the radius of the reference circle 32.

The Tacan 360 radiation pattern is represented in FIGURE 4 by polarcurve 35, in a typical azimuth plane, with point as the origin. Curve 35is the composite fundamental and nine loge modulation of the basicomnidirectional uniform 360 radio pattern represented by basic circle32. The pattern 35 is rotated about its origin at c to effect the Tacansystem results. The antenna of the present invention produces a rotatingspatially modulated Tacan pattern as represented by theFIGURES 1 through4.

FIGURE 5 illustrates the action of a Luneberg lens 40 on a single radiopoint source P. The Luneberg lens, as known in the art per se, is asphere of dielectric material in which the dielectric constant variesgradually with the radius from center c. It is densest, namely of thevalue 2.0 at the center, to least dense at the surface, namely with avalue of 1.0. In such a sphere 40, the index of refraction n of theradio waves 41 passing therethrough varies with the normalized radius raccording to the formula n= /2r At the microwave frequencies utilized inTacan transmission, namely, of the order of 1,000 megacycles, the lens40 produces a uniform emergent radio beam 42. Thus, any circularaperture at or near the lens, represented at A, along beam 42 will havea radio pattern of uniform phase and uniform amplitude.

FIGURE 6 represents the relative amplitude or signal strength 2 of abeam such as 42, when measured at angular deviations a with respect tothe beam (42) axis (fairly remotely from lens 40). It is noted, asFIGURE 6 curve 43 shows for a horizontal beam ('42), in that there is anelevation signal variation from the peak value ofe at 44 on the beamaxis 45. The main lobe of curve 43 in effect reaches the zero level atpoints indicated at 46, 46

which, depending upon the sphere diameter and other factors may occur,for example, at +6, +8", etc.

It is also to be noted that minor lobes 47-.-.47, 48-48 and 49-49 arealso represented in curve 43'for greater elevation deviation from ahorizontal beam (42). FIGURE 7 shows a polar curve 50 in elevation for ahorizontal beam (42) from a spherical lens (40). The

main lobe 51 extends uniformly above (52) and below (53) the beam axis54. The minor lobes 55, 56 and 57 correspond to those indicatedat 47,48, 49 in FIGURE 6. The relative signal strength 2 is determined by theintersection of curve 50 with the elevation line 58 at a degrees from avehicle V such as an aircraft.

An important feature of my invention is to utilize a radio microwavelens such as a Luneberg sphere and apply simultaneously thereto aninfinite numberof radio point sources along a circular region thereof.FIGURE 8 diagrammatically represents the'lens 60 with the multiple orinfinite radio point sources, P, P along the equatorial circle 61. Thelens center is 'at 'c, and its zenith at line 62.

The 360 array 61 of point sources, P, P produces a toroidal pattern ofan otherwise linear beam (42) due to a single point source noted abovein connection with FIGURE 5. For uniformly phased and equal amplituderadio point sources, P, P along circle 61, there results a symmetricaltoroid pattern having a common vertical polar configuration along anyelevation plane. Means are provided by my present invention tocompositely modulate and rotate such uniform toroid patterns toeffectuate the requisite Tacan specifications described in connectionwith FIGURES 1 through 4 hereinabove.

FIGURE 9 is a perspective illustration of a unifor-m continuous orinfinite point source feed or line for the microwave lens hereof. Thisfeed or line system comprises two spaced metal discs 62, 63 fed by acenter coaxial transmission line 64. A uniform axial radio source isprojected by the transmission discs 62, 63 as indicated by radial lines65, 65. Rotation of the disc array 62, 63 as indicated by arrow aeffects a direct spacial rotation of the source pattern 65. 1

, FIGURE 10 is a cross-sectional view through a simplified version ofthe invention Tacan antenna. 'The dielectric sphere 70 is of theLuneberg type with radial dielectric constant change, as described inconnection with lens 40 of FIGURE 5. Two discs 71, 72 are arrangedhorizontally along the diameter of sphere 70. A coaxial transmissionline with outer conductor 73 and inner conductor 74 couples to theopposed discs 71, 72 to feed a source of radio signals s to discs 71,72.

The signals from source .9 are indicated as moving to the discs 71, 72by arrow b, and then to radiate across the discs to their perimeters asindicated by arrows d, d as in the manner of FIGURE 9. The perimeterregion of each disc 71, 72 preferably, though not necessarily, extendsbeyond the surface of lens 70. A horn reflector band 75 surrounds theperiphery of discs 71, 72 to reflect the incident radio signal wavesback to the lens 70 along the sphere. This reflection by band 75 effectsthe infinite radio point sources along a circular path of sphere 70 inthe manner of FIGURE 8.

The reflector 75 is trough-shaped with a cross-section corresponding toa horn radiator. Horn reflector band 75 has a central flat region 76constituting the reflector section opposite the signal emergent regionof discs 71, 72, and two angular regions 77, 78 constituting the hornwalls. Properly matched construction will produce substantially totaltransmission into the lens as indicated by arrow e with negligiblereflection back into the narrowly spaced discs 71, 72 and withnegligible undesired transmission, for example as shown by arrow 1. Anefficient radio transmission system, with low VSWR is thus offected,providing the continuous point source band about lens 70. A Tacan typetoroidal pattern results. A series of beam modulator elements 80 areprovided along the transmission discs 71, 72. Elements 80 modulate theotherwise azimuthally uniform toroidal beam emanating from lens 70 withthe multiple lobes in accordance with FIGURE 4. An exemplary modulatorelement 80 is a bolt 80 mounted between discs 71, 72 in the radial pathof a portion of the radio waves therebetween.

FIGURE 11 is a plan view of the disc assembly 71, 72, showing the topdisc 71 and the multiple lobe modulator elements 80, 80. Nine elements80 produce nine uniform lobes (31). The desired amplitude of the lobesis determined by suitable radial spacing of the elements 80 on discs 71,72, their diameter, and their metal composition, as will now beunderstood by those skilled in the art. A tenth modulator bolt 81 islocated closer radially to center 0 of discs 71, 72 and constitutes thefundamental modulator for the lower frequency, corresponding to curve 33of FIGURES 3 and 4.

FIGURE 12 illustrates an enlarged cross-section of modulator bolt 80having nut 82 set between discs'71, 72.

For maximum utilization of the emitted signal strength, and also tobetter meet the six db gain requirement, the radio transmission discsare moved below the equatorial area of the spherical lens.

FIGURE 13 illustrates lens 85 with transmission discs 86, 87 set belowthe equatorial diameter88. The n'm reflector 89 surmounts the projectingperiphery of discs 86, 87. The coaxial signal s feed line 90 suitablycouples with discs 86, 87. It is noted that for Tacan operation, themodulator transmission disc combination is rotated about its zenithaxis, along 1;. The lens 85 and reflector 89 are preferably stationary.The-reflector 89 is advantageously supported on lens 85.

FIGURE 1 14 illustrates in polar formrthei-upward-tilt efiectedt-by thelowering of transmission discs 86:37: The. below :horizon area 92' ofcurve 91yis: reducedas compared: toyarea 53 of FIGURE-7. Furthemthe:5*"; elevation: line-intersection point, 94' :is. increased 1 in gainto: better meet. the requisitesix db. The curve 91 peakis.:shiftedz-close.- to the 5 li'ne. 94-, .though not-:necessaiily onit. a r FIGURES. 15 and 16 showalternate; forrnmfor: the lowering of thetransmission. circumference to: elfect the upward. beam tiltasperFIGURES 1-3, 14. The lens 1000f FIGURE 15 has two spaced conicalmetal members 101', 102, with a central coaxial feed line 103. Thereflector band 104 for lens 100 is shown asfl'at. This permits the coneperipheries to remain: interior of sphere 100. In sphere 105 of FIGURE16, the two conical metal: members 106, '107'havea common apex-position,as at center c. They are fed by line108. A trough horn-type reflectorband109 is used' therefor.

Another important feature of the invention antenna is to'be effective tothe 60 elevation line per FIGURE 1. This requires a smoothing in of thelobes 95, 95of FIGURE 14 polar curve and of the nullsbetween lobes asindicated in FIGURE 18 at shaded area 120. Thus," signals are radiatedabout the 360 toroidpattern tothe 60 altitude with minimumcosecant 121'magnitudes maintained.

In FIGURE 17 is shown one form of the antenna 'hereof which smooths inthe lobes 95. This antenna comprises a lens 1100f the Luneberg type withselected areas ofdifferent dielectn'c configuration. The modulatortransmission plate array shown is with spaced cones 111, 112; and hornrim reflector 113. In the upper section of lens 110;is a conical orother suitably shaped region 114 of greater dielectric constant materialthan that generally present in a Luneberg lens. In the lower lenssection, thereis a conical region 115 of material having a generallylower dielectric constant than present for a Luneberg lens.

The result of the denser dielectric region 114 and lighter dielectricregion 115 in sphere 110 is to change the minor lobed polarpattern, see95, 95 in FIGURE 14, to a. smoothed-in area indicated. irregularly as1211- in FIGURE 18. This causes a continuous cosecant-121 relation asdesired. Only the upper section of curve 122 is shown in FIGURE 18. Thelower minor lobe polar portion is not significant in the Tacan display.

Other methods and arrangements may be used to effect the smoothing oflobes 95 (FIGURE 14) into toroidal area. 120 (FIGURE. 18). For example,the horn sect-iomofreflector (89 of FIGURE 13) may have its upperportion tilted at an angle away from sphere (85) to tilt or modify thephase front of the energyemerging from the horn reflector.Alternatively, the shape of either the upper. or. the'lower section ofthe sphere (as at 85) and the dielectric constant within this sectionmay .be progressively. altered to effect such smoothing in (120') of thelobes (95).

While I have above illustrated the invention with the multiple radiopoint sources at or reasonably close to thesurface of the microwavelens, these may be different if the dielectric constant is varied withinthe lens in the proper manner as well known in the art.

FIGURE 19-illustrates these point sources represented by P remote fromlens 125. The resultant beam at aperture'A' is uniform as required.Also, the radio point sources, represented by P" in FIGURE 20 may bewell' within-. the lens 126. The resultant beam at apertureAis:uniform;.

A physical assembly of a Tacan antenna in accordance withmypinventionlhereof is illustrated in vertical cross section in FIGURE22. The lens 130 comprises .two hemispheresw131, 132 of dielectricmaterial. The practical-radial variation of the dielectric constant ofhemie.

' mission discs 140, 141 has no electrical function.

spheres-131; 132; in' the. .Lunebergylens' manner already described-,isunderstoodlby those skilled in the art and is notfdetailed. v

The upper hemisphere 131 has its center c spaced above thecenter c of:the lowerione 13-2. Open regions 13 3, 134 are formed betweenhemispheres 131, 132 to containithe rotatingrmodul'ator. transmissiondiscs. The hemispheres 1 31",? 132- are suitably fastened together byhardware 135,436. The assembly is-supported in a di-. electric supportcone 1371 on frame 1'38 mounted on base 139.

The rotatable spaced transmission metal discs..1'40, have a firm. foamdielectric layer 142. therebetween for composite support. The discs 140,141' are signal fed by. andfsecured with coaxial transmission line. 143,144. Innerconductor 143- is' connected to upper disc by": screw 145 andtransformer sleeve- 146. The outer conductor 144-connects by bracket 147to lower plate 141 Outer conductor 144 is: rotatably supported by rollerbearings 148; 149.

The coaxialline 143; 144iextends through hollow shaft motor 150.The-outer line-144 has a reduced diameter section- 144 that is rotatedby motor 150 and rotates discs 140, 14 1 at 900 rpm. Discs 140, 141 haveslab modulator elements 151', 151' to perform the results of bOlts SO ofthe other modifications described above. The ringreflector 152 is flatas in FIGURE. 15. A motor speed regulator is preferably employed tostabilize the rotation at requisite uniform speed. A sine wave generator152, a pulse generator 153 and rotary electrical line coupler 154are'mounted beneath motor 150; The pulse generator 153 uses a disc 155having elements 156 to effect the Tacan signal triggering.

The foam dielectric between the rotating radio trans"- Its dielectricconstant is thus kept low, such as 1.05 A firm' foamlayer of styrene issuitable. The pulse generator- 153and the sine generator 152 areconnected to the Tacan electrical and electronic equipment (not shown),in the usual manner. The pulse generator 153 comprises a disc 155 ofdielectric material with nine metallic members 156 spaced near itsperiphery 40 apart.

FIGURE 21 shows this arrangement. Disc 155 is secured to therotatingcentral transmission line at hub 157. The rotating trigger members 156coact with the stationary yoke-158" toeffect the identifying timedpulses for the-distance measurement determinations ofthe mov ingvehicle. The fundamental frequency triggering is per.- formed by passageof member 159.

The basic microwave signal to be modulated and broadcasted by theantenna system thereof is fed by a coaxial transmission line into theinput of rotary coupler 154. The radio signal, at the selected Tacanbroadcast frequency, is thus fed to internal'rotating coaxial cable143,- 144 through the coupler 154. Suitable matching transformations aremaintained to the coupler 154,. through the motor with the line 143,144, and on to the rotating discs. The discs rotate unhindered. in. theclearspace set thereabout within lens 130..

The antenna systemof my invetnion is not frequency sensitive over theTacan microwave band, and accordingly one basic construction can be usedfor all Tacan andf Vortac installations, regardless of the frequencyselected to transmit. The radial distance of'the modulatorele ments maybe shifted in some cases, before installation, for some selectedfrequency region. Pre-drilled' series of openings for this purpose maybe provided.

In a physical embodiment of the invention antenna, a Luneberg-typesphere 'wasused, 18" in'diameter. The rotatable radio transmission discswere located below the sphere center and-coaxial with its zenith, being26" 'in di-- ameter to 1 project .beyond the sphere. spacedi interiorly.

A horn-sectioned reflector ring surrounded the. project ing, periphery;of the transmission discs, with an outer These discs were circumferenceof 27". Thus, the outer horn rim was V2" from the disc periphery. Thereflector base opening was about 4" across, and supported on the sphere.The modulator bolt elements were mounted at a radius of 8 /2" from thecenter of the discs; with the fundamental modulator at 2 radius.

While I have described my invention in connection with several exemplaryembodiments, modifications and variations thereof may be made Withoutdeparting from the broader spirit and scope of the invention, asdescribed in the following claims.

I claim:

1. A transmitter antenna comprising a radio wave lens extending for 360about its zenith, a radio transmission structure rotatable with respectto said lens for applying impressed signal energyabout a 360 segment ofsaid lens, said structure including a pair of opposed metallic platessupported within the lens, and motor means for continuously rotatingsaid transmission structure, said metallic plates being supportedhorizontally within the lens at a position below the equatorial plane ofthe lens to eflectuate an upwards tilt of the radiated radio pattern.

2. A transmitter antenna of the character described comprising amicrowave lens composed of a generally spherical body of dielectricmaterial having its dielectric constant vary substantially inverselywith its radial extent from a central value of 2 to a peripheral valueof 1, a radio transmission structure rotatably supported within the lenssymmetrically about its zenith diameter to radiate radio energy along ahorizontal 360 spherical segment, a reflector rim arranged about saidsegment to reflect the 360 beam energy through the lens and produce agenerally toroidal radiation pattern about the sphere zenith, modulatorelements mounted with said structure to amplitude modulate the radiatedpattern, a coaxial transmission line coupled to said structure androtatably supported insaid spherical body along its zenith diameter, anelectrical coupler for the coaxial line, and motor means connected tosaid coaxial line to continuously rotate said line and structure toproduce a rotating amplitude space modulated toroidal radiation pattern.

3. A transmitter antenna as claimed in claim 2, in which the region ofsaid dielectric spherical body about the rotatable structure is hollow.

4. A transmitter antenna as claimed in claim 2, in which the upperhemispherical portion of said body is spaced from the lowerhemispherical portion thereof.

5. A transmitter antenna as claimed in claim 4, in which the said radiotransmission structure is centered below the center of the lowerhemispherical portion.

6. A transmitter antenna as claimed in claim 2, in which the upperportion of the dielectric body is deformed from the spherical form toemphasize the radiated pattern strength at the upper altitude angles.

7. A transmitter antenna as claimed in claim 2, in which the upperhemispherical portion of the dielectric body contains a region ofdielectric material substantially greater than that of the body materialsurrounding it to emphasize the radiated pattern strength at the upperaltitude angles.

8. A transmitter antenna comprising a microwave lens composed of agenerally spherical body of dielectric material, a radio transmissionstructure rotatably supported within the lens symmetrically about itszenith diameter to radiate radio signal energy along a horizontal 360spherical segment, a reflector arranged about said segment to reflectthe 360 signal energy through the lens and produce a generally toroidalradiation pattern about the lens zenith, modulator elements mounted withsaid structure to amplitude modulate the 360 radiated pattern,transmission line means coupling signal energy to said interiorstructure, and motor means for rotating'said'structure and elements toproduce a rotating amplitude space modulated toroidal radiation pattern.

9. A transmitter antenna comprising a microwave lens within the lenssymmetrically about its zenith diameter.

composed of a generally spherical body of dielectric material, a radiotransmission structure rotatablysupported within the lens symmetricallyabout its zenith diameter to radiate radio signal energy along ahorizontal 360 spherical segment, a reflector arranged about saidsegment to reflect the 360 signal energy through the lens and produce agenerally toroidal radiation pattern about the lens zenith, modulatorelements mounted with said structure to amplitude modulate the 360radiated pattern, transmission line means coupling signal energyto saidinterior structure, and motor means forrotating said structure andelements to produce a rotating amplitude space modulated toroidalradiation pattern, in which the radio transmission structure includes apair of opposed metallic plates providing a 360 signal radialtransmission line.

10. A transmitter antenna comprising a microwave lens composed of agenerally spherical body of dielectric material, a radio transmissionstructure rotatably supported within the lens symmetrically about itszenith diameter to radiate radio signal energy along a horizontal 360spherical segment, a reflector arranged about said segment to reflectthe 360 signal energy through the lens and produce a generally toroidalradiation pattern about the lens zenith, modulator elements mounted withsaid structure to amplitude modulate the 360 radiated pat-tern,transmission line means coupling signal energy to said interiorstructure, and motor means for rotating said structure and elements toproduce a rotating amplitude space modulated toroidal radiation pattern,in which the radio transmission structure includes a pair of opposedmetallic plates providing a 360 signal radial transmission line; withsaid reflector arranged adjacent the lens surface and opposite theperipheral region of said plates and directed to effect the saidreflection of the radially radiated structure signal energy into thelens.

11. A transmitter antenna comprising a microwave lens composed of agenerally spherical body of dielectric material, a radio transmissionstructure rotatably supported within the lens symmetrically about itszenith diameter to radiate radio signal energy along a horizontal 360spherical segment, a reflector arranged about said segment to reflectthe 360 signal energy through the lens and produce a generally toroidalradiation pattern about the lens zenith, modulator elements mounted withsaid structure to amplitude modulate the 360 radiated pattern,transmission line means coupling signal energy to said interiorstructure, and motor means for rotating said structure and elements toproduce a rotating amplitude space modulated toroidal radiation pattern,in which said reflector is arranged adjacent the lens surface andopposite the peripheral region of said structure and directed to effectthe said reflection of the radially radiated structure signal energyinto the lens.

12. A transmitter antenna comprising a microwave lens composed of agenerally spherical body of dielectric material, a radio transmissionstructure rotatably supported within the lens symmetrically about itszenith diameter to radiate radio signal energy along a horizontal 360spherical segment, a reflector arranged about said segment to reflectthe 360 signal energy through the lens and produce a generally toroidalradiation pattern about the lens zenith, modulator elements mounted withsaid structure to amplitude modulate the 360 radiated pattern,transmission line means coupling signal energy to said interiorstructure, and motor means for rotating said structure and elements toproduce a rotating amplitude space modulated toroidal radiation pattern,in which said transmission line means includes a coaxial linemechanically and electrically coupled to said structure and connectedwith said motor means.

13. A transmitter antenna comprising a microwave lens composed of agenerally spherical body of dielectric material, a radio transmissionstructure rotatably supported to radiate radio signal energy along ahorizontal 360 9 spherical segment, a reflector arranged about saidsegment to reflect the 360 signal energy through the lens and produce agenerally toroidal radiation pattern about the lens zenith, modulatorelements mounted with said structure to amplitude modulate the 360radiated pattern, transmission line means coupling signal energy to saidinterior structure, and motor means for rotating said structure andelements to produce a rotating amplitude space modulated toroidalradiation pattern, in which the radio transmission structure includes apair of opposed metallic plates providing a 360 signal radialtransmission line, with said reflector arranged adjacent the lenssurface and opposite the peripheral region of said plates and directedto efiect the said reflection of the radially radiated structure signalenergy into the lens, in which said transmission line means includes acoaxial line mechanically and electrically coupled to said structure andconnected with said motor means said coaxial line extending along thezenith diameter of the lens.

References Cited in the file of this patent UNITED STATES PATENTS

